Air conditioning apparatus

ABSTRACT

An air conditioning apparatus is provided whereby the pressure pulsation generated by a compressor can be entirely reduced both during cooling and during heating, and a muffler can be shared. The air conditioning apparatus has a refrigerant circuit. The refrigerant circuit is configured so that a compressor for compressing a refrigerant, an indoor heat exchanger, an outdoor heat exchanger, and a four-way switch valve are connected via a refrigerant pipe. The four-way switch valve switches the flow of refrigerant compressed by the compressor to either the indoor heat exchanger or the outdoor heat exchanger. The air conditioning apparatus further includes a pressure pulsation reducing component. The pressure pulsation reducing component is provided between the four-way switch valve and the indoor heat exchanger. The pressure pulsation reducing component reduces pressure pulsation inside the refrigerant circuit. The pressure pulsation is generated by the compressor.

TECHNICAL FIELD

The present invention relates to an air conditioning apparatus provided with a refrigerant circuit that includes a compressor.

BACKGROUND ART

Conventional refrigerant circuits have problems in that pressure pulsation generated by a compressor is propagated through a refrigerant pipe into an indoor refrigerant pipe near the indoor units, and vibration and/or abnormal noise is generated from the indoor refrigerant pipe arid the indoor units. An air conditioning apparatus has therefore been disclosed in Patent Document 1, in which a single muffler is provided between the compressor and a four-way switch valve in order to suppress the propagation of pressure pulsation to the indoor refrigerant pipe.

<Patent Document 1> Japanese Laid-open Patent Publication No. 9-250831

DISCLOSURE OF THE INVENTION Problems the Invention is Intended to Solve

In the case of the air conditioning apparatus disclosed in Patent Document 1, the pressure pulsation can be reduced by the muffler when the pulsation generated by the compressor is directed toward the indoor units via the four-way switch valve (i.e., in the ease of suction pulsation during heating, and exhaust pulsation during cooling). However, when the pulsation generated by the compressor is directed toward the indoor units and not through the four-way switch valve (i.e., in the case of exhaust pulsation during heating, and suction pulsation during cooling), the pressure pulsations do not pass through the muffler, and it is therefore impossible both during cooling and heating to entirely reduce the pressure pulsation generated by the compressor through the use of the muffler before the pressure pulsation reaches the indoor refrigerant pipe near the indoor units.

Further, providing a muffler to both the suction side and the exhaust side of the compressor has a problem in that it increases the number of components and the manufacturing cost.

An object of the present invention is to provide an air conditioning apparatus wherein the pressure pulsation generated by the compressor can be entirely reduced during cooling as well as during heating and it is capable of muffler sharing.

Means for Solving These Problems

An air conditioning apparatus according to a first aspect of the present invention is an air conditioning apparatus comprising a refrigerant circuit. The refrigerant circuit is configured so that a compressor for compressing a refrigerant, an indoor heat exchanger, an outdoor heat exchanger, and a four-way switch valve are connected via a refrigerant pipe. The four-way switch valve switches the flow of refrigerant compressed by the compressor to either the indoor heat exchanger ox the outdoor heat exchanger. The air conditioning apparatus further comprises a pressure pulsation reducing component. The pressure pulsation reducing component is provided between the four-way switch valve and the indoor heat exchanger. The pressure pulsation reducing component reduces pressure pulsation inside the refrigerant circuit. The pressure pulsation is generated by the compressor.

In this configuration, since the pressure pulsation reducing component is provided, between the four-way switch valve and the indoor heat exchanger, the pressure pulsation generated by the compressor can be entirely reduced before reaching the indoor refrigerant pipe both during cooling and during heating in the case of an air conditioning apparatus that switches between cooling and heating. Further, a muffler used tor reducing pressure pulsations can be shared, and the number of components can be reduced.

An air conditioning apparatus according to a second aspect of the present invention is the air conditioning apparatus of the first aspect, wherein the pressure pulsation reducing component is provided within an outdoor unit. The compressor and the outdoor heat exchanger are housed in the outdoor unit.

Since the pressure pulsation reducing component is provided within the outdoor unit in which the compressor and the outdoor heat exchanger are housed, the pressure pulsation reducing component is easily installed and maintained. Moreover, since the pressure pulsation reducing component is installed at the position near the compressor, which is the source of the pressure pulsation, within the refrigerant circuit, the pressure pulsation reducing effects thereof are significant.

An air conditioning apparatus according to a third aspect of the present invention is the air conditioning apparatus of the first or second aspect, wherein the refrigerant is CO₂.

In this configuration, CO₂ is used as the refrigerant, and pressure pulsations are more significant compared with other refrigerants, but pulsations can be reduced both during cooling and during heating by the pressure pulsation reducing component provided between the four-way switch valve and the indoor heat exchanger. A CO₂ refrigerant has low global warming potential and enables products that are environmentally friendly. The CO₂ refrigerant also has high refrigeration capacity per unit volume, and a cylinder tor achieving the same capacity as other refrigerants can be reduced in size, and the compressor can also be reduced in size.

An air conditioning apparatus according to a fourth aspect of the present invention is the air conditioning apparatus of any of the first through third aspects, wherein the pressure pulsation reducing component is a vessel having a muffler function.

In this configuration, since the pressure pulsation reducing component is a vessel having a muffler function, not only can pressure pulsations be reduced, but liquid-vapor separation of the refrigerant is also possible inside the vessel.

An air conditioning apparatus according to a fifth aspect of the present invention is the air conditioning apparatus of any of the first through fourth aspects, wherein the pressure pulsation reducing component is one component selected from the group consisting of an expansion muffler, a π-type filter, a side branch muffler, a Helmholtz muffler, and an interference muffler.

In this configuration, because the pressure pulsation reducing component is one component selected from the group consisting of an expansion muffler, a π-type filter, a side branch muffler, a Helmholtz muffler, and an interference muffler, pressure pulsation can be effectively reduced using these conventionally known mufflers.

Effect of the Invention

According to the first aspect, the pressure pulsation generated by the compressor can be entirely reduced before reaching the indoor refrigerant pipe both during cooling and during heating. A muffler used for reducing pressure pulsations can also be shared, and the number of components can be reduced.

According to the second aspect, the pressure pulsation reducing component is easily installed and maintained, and the pressure pulsation reducing effects of the pressure pulsation reducing component are significant.

According to the third aspect, although pressure pulsations are more significant compared with other refrigerants, pulsations can be reduced both during cooling and during heating by the pressure pulsation reducing component provided between the four-way switch valve and the Indoor heat exchanger. A CO₂ refrigerant has low global warming potential and enables products that are environmentally friendly. A CO₂ refrigerant also has high refrigeration capacity per unit volume, and a cylinder for achieving the same capacity as other refrigerants can be reduced in size, and the compressor can also be reduced in size.

According to the fourth aspect, not only can pressure pulsations be reduced, but liquid-vapor separation of the refrigerant is also possible inside the vessel.

According to the fifth aspect, pressure pulsation can be effectively reduced using a conventionally known muffler.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing an air conditioning apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an expansion muffler as a specific example of a pressure pulsation reducing component of FIG. 1.

FIG. 3 is a schematic diagram showing a π-type filter as a specific example of the pressure pulsation reducing component of FIG. 1.

FIG. 4 is a schematic diagram showing a side branch muffler as a specific example of the pressure pulsation reducing component of FIG. 1.

FIG. 5 is a schematic diagram showing a Helmholtz muffler as a specific example of the pressure pulsation reducing component of FIG. 1.

FIG 6 is a schematic diagram showing an interference muffler as a specific example of the pressure pulsation reducing component of FIG 1.

KEY

1 air conditioning apparatus 2 compressor 3 indoor heat exchanger 4 outdoor heat exchanger 5 four-way switch valve 6 refrigerant pipe 7 refrigerant circuit 8 pressure pulsation reducing component 9 outdoor unit

BEST MODE FOR CARRYING OUT THE INVENTION

An air conditioning apparatus 1 shown in FIG. 1 is capable of both a cooling operation and a heating operation, and is provided with a refrigerant circuit 7 configured so that a compressor 2 for compressing a CO₂ refrigerant; an indoor heat exchanger 3; an outdoor heat exchanger 4; a four-way switch valve 5 for switching the flow of refrigerant compressed by the compressor 2 to either the indoor heat exchanger 3 or outdoor heat exchanger 4; and an electromagnetic expansion valve 10 are connected via a refrigerant pipe 6. The air conditioning apparatus 1 is further provided with a pressure pulsation reducing component 8 for reducing pressure pulsation that is generated by the compressor 2 within the refrigerant circuit 7.

The pressure pulsation reducing component 8 is provided between the four-way switch valve 5 arid the indoor heal exchanger 3. Therefore, the pressure pulsation generated by the compressor can be entirely reduced both during cooling and during healing in the case of the air conditioning apparatus 1 that switches between cooling and heating. The muffler used for reducing pressure pulsations can also be shared, and the number of components can be reduced.

The pressure pulsation reducing component 8 is provided within an outdoor unit 9 in which the compressor 2 and outdoor heat exchanger 4 are housed.

In the air conditioning apparatus 1, CO₂ is used as the refrigerant. The pressure pulsations of a CO₂ refrigerant are more significant than the pressure pulsations of other refrigerants, but pulsations can be reduced both during cooling and during heating by the pressure pulsation reducing component 8 provided between the four-way switch valve 5 and the indoor heat exchanger 3.

The pressure pulsation reducing component 8 is specifically one component selected from the group consisting of an expansion muffler, a π-type filter, a side branch muffler, a Helmholtz muffler, and an interference muffler.

As shown in FIG. 2, an expansion muffler 21 has an expansion portion 21 a and straight pipe portions 21 b connected on both sides thereof. The cross-sectional area S2 of the expansion portion 21 a is larger than the cross-sectional area S1 of the straight pipe portions 21 b.

The value of the transmission loss TL of the expansion muffler 21 is indicated by the equation below.

TL=10×log(1+¼×(m−1/m)²×sin²(K×L1))  (Eq.1)

In the equation, L1 is the length of the expansion portion 21 a, m=S2/S1, and k=2πf/c, wherein c is the speed of sound.

As shown in FIG. 3, a π-type filter 22 has a first expansion portion 22 a, a second expansion portion 22 b, a connecting pipe portion 22 c, a first straight pipe portion 22 d, and a second straight pipe portion 22 e. The connecting pipe portion 22 c connects the first expansion portion 22 a and the second expansion portion 22 b. The first straight pipe -portion 22 d is connected on the opposite side from the connecting pipe portion 22 c in the first expansion portion 22 a. The second straight pipe portion 22 e is connected on the opposite side from the connecting pipe portion 22 c in the second expansion portion 22 b. Each of the cross-sectional areas of the first expansion portion 22 a and the second expansion portion 22 b are larger than cross-sectional areas S3, S4 of the connecting pipe portion 22 c, and the first straight pipe portion 22 d and second-straight pipe portion 22 e, respectively.

The value of the transmission loss TL of the π-type filter 22 is as shown below. (Note that L2 is the length of the connecting pipe portion 22 c, V1 is the volume of the first expansion portion 22 a, V2 is the volume of the second expansion portion 22 b, S3 is the cross-sectional area of each of the first straight pipe portion 22 d and the second straight pipe portion 22 e, and S4 is the cross-sectional area of the connecting pipe portion 22 c.)

TL=10×log(σ²)  (Eq. 2)

In the equation, σ=V²×ω³×L2/(S3×S4×c³), wherein c is the speed of sound.

As shown in FIG. 4, a side branch muffler 23 has a branch, portion 23 a and a straight pipe portion 23 b. The brunch portion 23 a branches at a right angle from the straight pipe portion 23 b.

The frequency f of the side branch muffler 23 is as shown below.

f=c/(4×L3)  (Eq. 3)

In the equation, L3 is die length of the branch portion 23 a, and c is die speed of sound.

As shown in FIG. 5, a Helmholtz muffler 24 has an expansion portion 24 a, a connecting pipe portion 24 b, and a straight pipe portion 24 c. The connecting pipe portion 24 b branches at a right angle from the straight pipe portion 24 c. The connecting pipe portion 24 b connects the expansion portion 24 a and the straight pipe portion 24 c. The cross-sectional area of the expansion portion 24 a is larger than the cross-sectional area of each of the connecting pipe portion 24 b and the straight pipe portion 24 c.

The frequency f of the Helmholtz muffler 24 is as shown below.

F=c/2π×√(S5/(V3×L4))  (Eq. 4)

In the equation, V3 is the volume of the expansion portion 24 a, S5 is the cross-sectional area of the connecting pipe portion 24 b, L4 is the length of the connecting pipe portion 24 b, and c is the speed of sound.

As shown in FIG. 6, an interference muffler 25 has a curved pipe portion 25 a that extends in an arch, and a straight pipe portion 25 b. Both ends of the curved pipe portion 25 a are connected to the straight pipe portion 25 b.

The half wavelength λ/2 of the interference muffler 25 is in the relationship as shown below:

λ/2=L5−L6  (Eq. 5)

In the equation, L5 is the pipe length of the curved pipe portion 25 a, and L6 is the pipe length of the straight pipe portion 25 b.

<Characteristics>

(1) In the air conditioning apparatus 1 according to the embodiment, since the pressure pulsation reducing component 8 is provided between the four-way switch valve 5 and the indoor heat exchanger 3, the pressure pulsation generated by the compressor 2 can be entirely reduced before reaching the indoor refrigerant pipe both during cooling and during heating in the case of the air conditioning apparatus 1 that switches between cooling, and heating. The muffler used for reducing pressure pulsations can also be shared, thereby the number of components can be reduced.

Particularly in a ceiling-mounted indoor unit or room air conditioner, the length of the refrigerant pipe is relatively small, and the indoor refrigerant pipe tends to vibrate and readily generate noise, but pressure pulsation can be effectively reduced in the air conditioning apparatus 1 of the present embodiment in such a case.

(2) In the air conditioning apparatus 1 of the present embodiment, since the pressure pulsation reducing component 8 is provided within an outdoor unit 9 in which the compressor 2 and the outdoor heat exchanger 4 are housed, the pressure pulsation reducing component 8 is easily installed and maintained. Further, since the pressure pulsation reducing component 8 is installed at a position near the compressor 2, which is the source of the pressure pulsation, within the refrigerant circuit 7, the pressure pulsation reducing effects thereof are significant.

(3) In the air conditioning apparatus 1 of the present invention, CO₂ is used as the refrigerant, and although pressure pulsations are more significant compared with other refrigerants, pulsations can be reduced both during cooling and during heating by the pressure pulsation reducing component 8 provided between the four-way switch valve 5 and the indoor heat exchanger 3. A CO₂ refrigerant has low global warming potential and enables products that are environmentally friendly. A CO₂ refrigerant also has high refrigeration capacity per unit volume, and a cylinder for achieving the same capacity as other refrigerants can be reduced in size, and the compressor can also be reduced in size.

(4) In the air conditioning apparatus 1 of the present embodiment, the pressure pulsation reducing component 8 is one component selected from the group that consists of an expansion muffler, a π-type filter, a side-branch muffler, a Helmholtz muffler, and an interference muffler; and pressure pulsation can therefore be effectively reduced using these conventionally known mufflers.

<Modification>

The pressure pulsation reducing component 8 may also be a component that has a function in addition to a muffler function. For example, the pressure pulsation reducing component 8 may be a vessel having a muffler function. In this case, not only can pressure pulsations be reduced, but liquid-vapor separation of the refrigerant is also possible inside the vessel.

The vessel having a muffler function may also be one component selected from the above-described group that consists of an expansion muffler, a π-type filter, a side-branch muffler, a Helmholtz muffler, and an interference muffler.

INDUSTRIAL APPLICABILITY

The present invention can be widely used in air conditioning apparatus provided with a refrigerant circuit that includes a compressor. 

1. An air conditioning apparatus, comprising: a refrigerant circuit having a compressor being configured to compress a refrigerant, an indoor heat exchanger, an outdoor heat exchanger, and a four-way switch valve being configured to switch the flow of refrigerant compressed by the compressor to either the indoor heat exchanger or the outdoor heal exchanger, the compressor, the indoor heat exchanger, the outdoor heat exchanger, and the four-way switch valve being connected via a refrigerant pipe; and a pressure pulsation reducing component being provided between the four-way switch valve and the indoor heat exchanger and configured to reduce pressure pulsation inside the refrigerant circuit generated by the compressor.
 2. The air conditioning apparatus according to claim 1, wherein the pressure pulsation reducing component is provided within an outdoor unit configured to house the compressor and the outdoor heat exchanger therein.
 3. The air conditioning apparatus according to claim 2, wherein the refrigerant is CO₂.
 4. The air conditioning apparatus according to claim 3, wherein the pressure pulsation reducing component is a vessel having a muffler function.
 5. The air conditioning apparatus according to claim 4, wherein the pressure pulsation reducing component is one component selected from the group consisting of an expansion muffler, a π-type filter, a side branch muffler, a Helmholtz muffler, and an interference muffler.
 6. The air conditioning apparatus according to claim 3, wherein the pressure pulsation reducing component is one component selected from the group consisting of an expansion muffler, a π-type filter, a side branch muffler, a Helmholtz muffler, and an interference muffler.
 7. The air conditioning apparatus according to claim 2, wherein the pressure pulsation reducing component is a vessel having a muffler function.
 8. The air conditioning apparatus according to claim 7, wherein the pressure pulsation reducing component is one component selected from the group consisting of an expansion muffler, a π-type filter, a side branch muffler, a Helmholtz muffler, and an interference muffler.
 10. The air conditioning apparatus according to claim 1, wherein the refrigerant is CO₂.
 11. The air conditioning apparatus according to claim 10, wherein the pressure pulsation reducing component is a vessel having a muffler function.
 12. The air conditioning apparatus according to claim 11, wherein the pressure pulsation reducing component is one component selected from the group consisting of an expansion muffler, a π-type filter, a side branch muffler, a Helmholtz muffler, and an interference muffler.
 13. The air conditioning apparatus according to claim 10, wherein the pressure pulsation reducing component is one component selected from the group consisting of an expansion muffler, a π-type filter, a side branch muffler, a Helmholtz muffler, and an interference muffler.
 14. The air conditioning apparatus according to claim 1, wherein the pressure pulsation reducing component is a vessel having a muffler function.
 15. The air conditioning apparatus according to claim 14, wherein the pressure pulsation reducing component is one component selected from the group consisting of an expansion muffler, a π-type filter, a side branch muffler, a Helmholtz muffler, and an interference muffler.
 16. The air conditioning apparatus according to claim 1, wherein the pressure pulsation reducing component is one component selected from the group consisting of an expansion muffler, a π-type filter, a side branch muffler, a Helmholtz muffler, and an interference muffler. 